1. Field of the Invention
This invention relates to a light switch and in particular to a solid-state light switch designed to control automatically lamps such as table and floor lamps.
2. Prior Art
The use of timers for turning on and off lights to simulate the occupancy of rooms and homes is well known. Numerous patents have issued describing such structures. Thus, U.S. Pat. No. 3,979,601 issued Sept. 7, 1976 discloses a combination dimmer and timer switch mechanism which is capable of turning on and off the power to a plug-in receptacle in accordance with a predetermined time switch. U.S. Pat. No. 4,151,515 issued Apr. 24, 1979 discloses a similar structure which not only reduces energy consumption by turning lights off after business hours, but also cycles lights in a predetermined manner to discourage burglaries. These structures are limited in that the pattern set for one day repeats on adjacent days unless the system is reset daily. Accordingly, a system designed to simulate occupancy can, by its precise repetitiveness, indicate to a keen observer that the building is not occupied.
In addition, occupants of buildings typically dim lights as well as turn them on and off. Prior art programmable switches which lack this ability are unable to simulate accurately the occupancy of a building.
Co-pending application Ser. No. 408,330 filed Aug. 16, 1982 and assigned to Security Switch, Ltd., discloses an invention which randomly turns on and off a light within a selected range of a desired time and also is capable of being programmed to dim the light at prearranged times to simulate accurately the occupancy of the building. However, the prior art switches including the switch described in the co-pending application Ser. No. 408,330 require adjustment to reflect the seasonal changes in the time of nightfall.